The objectives of this project are to enhance the basic knowledge of processes involved in the generation of event-related slow potentials, to study the functional relationships between event-related slow potentials and behavior, and to provide information regarding the mechanisms of alteration of these brain potentials by drugs. Using the rat as the experimental model, event-related potentials associated with conditioned stimuli will be measured in various behavior paradigms. Reinforcement will consist of food or rewarding brain stimulation. The relationship between slow potential responses and behavioral performance will be investigated. The effects of several psychoactive drugs will be studied in an attempt to understand the role of various neurotransmitters in the genesis of event-related slow potentials. Neuronal activity correlates of slow potential responses will be examined under non-drug and drug conditions. It is anticipated that this research will provide information which can aid in interpretation of the functional significance of the human CNV (contingent negative variation).